designating or of the third and last geologic epoch of the Paleogene, characterized by cold climate, the formation of vast grasslands, and the further development of mammals
Origin of Oligoceneoligo- + -cene
the Oligocene Epoch or its rocks
Of, relating to, or being the epoch of geologic time from about 34 to 23 million years ago, the third epoch of the Tertiary Period. It is characterized by further development of modern mammals, including the rise of the true carnivores and their gradual replacement of the creodonts. See Table at geologic time.
The Oligocene Epoch.